Figure 11.
Model for the action of phosphate (Pi) and the concentration of c-di-GMP (cdG) on activation of PvpsL and biofilm formation. (A) The level of cdG controls the transition of V. cholerae from the motile to the biofilm lifestyle. Although VpsR dimers bind the DNA in the absence or presence of cdG, only the VpsR dimers formed in the presence of cdG are transcriptionally active with RNAP at PvpsL. Formation of this complex results in a different interaction of VpsR with the DNA as observed by the DNase I footprints (indicated by the change of the VpsR dimer conformation). (B) While cdG is required for active VpsR formation, higher levels of Pi tip the balance toward more active VpsR, which then increases transcription. Thus, the level of Pi also participates in the decision between the motile and biofilm lifestyles.